Search engines are powerful tools for locating and retrieving documents from the Internet (or an intranet). Traditionally, different users who submit the same search query to a search engine receive the same set of search results. For example, the search engine generates the same set of search results for the search query “apple” irrespective of whether the search query is from a user who is interested in Apple® computers or from a user who is interested in the fruit malus domestica. Clearly such search results are likely to include some results of little interest to either user.
In view of the aforementioned, it would be desirable to have a search engine that can customize its search results so as to highlight information items in the search results that are most likely to be of interest to users who submit the search queries. Further, it would be desirable for such a system to operate without explicit input from a user with regard to the user's personal preferences and interests, and for the system to protect the privacy interests of its users.